But Manhattan really is New York City's heart though: the heart of a celebrated architecture, many exceptional museums and all types of dance, theatre, music and other arts; the heart of American financial district; the heart of all imaginable types of eating and drinking at any time of day; the heart of shopping...

Downtown Manhattan references
The statue of Liberty and Ellis Island
The Financial District: New York Stock Exchange, Wall Street and its surroundings
Brooklyn Bridge
Chinatown
Citty Hall
Little Italy
SoHo (New Museum of Contemporary Art)
Greenwich Village
The East Village
Times Square and the Theater District: Broadway, etc.
Chelsea district
The Lower East Side
Former World Trade Center

Midtown Manhattan references
Empire State Building
Penn Station
New York Library
Rockefeller Center
Grand Central Station
United Nations Buildings
Museum of Modern Art
Lincoln Center
Metropolitan Museum of Art
American Museum of Natural History
Central Park

Uptown Manhattan referencesGuggenheim Museum
Central Park
Columbia University
Cathedral of St. John the Divine
Harlem

New York weather is very changeable with moderate precipitation all year long, some heat waves in the summer and very cool weather in the winter and early spring. Snow is concentrated in the winter months, but not precipitation.
Considering the weather issue alone, then the best time to visit New Yorkwould be spring - April, May, June – or late-summer and early-fall – September, October - when Central Park becomes particularly beautiful-
However, there are, of course, other issues when considering a visit to New York. So, it all depends on what you value most. For some people, there is nothing like Christmas time to experience Times Square, the Rockefeller Center and the city’s shopping ambiance.